The present invention relates to an apparatus and a method for inserting flat, flexible, self-sealing valves between front and back panels of inflatable bodies such as novelty balloons or dunnage bags. More particularly, this invention relates to a method and apparatus for inserting such a valve between a front and back panel of an inflatable body without requiring that the valve be initially tacked or otherwise permanently attached to one of the panels prior to conveying the panels to a die station which forms the completed inflatable body.
Currently, there are many types of inflatable bodies that are mass produced and easier methods for producing inflatable bodies are useful in reducing the costs associated with mass production. One example is novelty balloons of the metalized mylar or nylon type that typically have a front panel and back panel sealed together about their periphery to form an inflatable body, typically inflated with a lighter-than-air gas or air. Such balloons often have novelty messages such as "Happy Birthday", "Happy Anniversary", "I Love You" and the like printed thereon and have become quite popular. Another example are inflatable dunnage bags that are a substitute for discrete packing materials and used for bearing against delicate or fragile articles in closed containers during shipment. Such inflatable dunnage bags, typically air-filled, are greatly advantageous over prior packing systems such as filling boxes with so-called styrofoam "popcorn" materials which are harmful to the environment.
With novelty balloon and dunnage bag products, it is known to use an elongated, self-sealing valve comprised of top and bottom layers of flexible plastic film sealed together along their edges to create a valve inlet, a valve outlet, and a passage therethrough. However, merely placing a self-sealing valve between the front and back panels of an inflatable body during the film conversion process has proven to be less than successful for manufacturing such products. This is because, if the valve is simply laid upon one of the webs, vibrations in the machinery, wind or air currents, gravity, and a variety of other factors can cause the valve to move out of position relative to the web, thereby resulting in the valve being sealed between the body's panels in a misaligned fashion. Such products, when formed with misaligned or otherwise improper valve, are non-usable and create wastage.
One method known in the art to prevent the above problems is to initially tack seal or otherwise permanently attach the valve to one of the panels or webs during the conversion process at a time prior to sealing the panels together to form the inflatable body. U.S. Pat. No. 4,917,646, issues to Kieves, is illustrative of such an initial tack sealing method. That patent discloses a valve that has a positioning tab which can be tacked with a heat seal during the manufacturing process directly to one of the two film webs. Although tacking the valve to one of the panels prevents valve misalignment, the method is less than successful from a manufacturing viewpoint as it requires the complexity and expense of providing an extra heat seal and extra die station.
An important aspect of this invention therefore lies in providing a method and apparatus for manufacturing an inflatable body with a self-sealing flexible valve which does not require that the valve be initially tack-sealed or otherwise permanently pre-attached to one of the panels prior to conveying the film webs to a die station and forming the inflatable body from the panels. Briefly, the method of this invention comprises the steps of forming the self-sealing flexible valve, conveying the upper and lower webs of sheet material through a conveyor assembly initially in a contiguous relation, and then conveying the webs of sheet material to a spreader bar which projects between the peripheral edges of the web to form a peripheral open zone between the webs. The webs are then separated at the open zone, and the valve is inserted between the top and bottom webs. Thereafter, the webs are conveyed past the spreader bar and brought back into a contiguous relation so that the webs frictionally retain the valve therebetween in the proper position where the valve was placed. The webs and frictionally clamped valve are then conveyed to a die station without any permanent pre-attachment of the valve to either of the webs. At the die station, the perimeter of an inflatable body shape is heat sealed onto the webs and valve such that the valve is simultaneously heat sealed to both the webs.
In one embodiment of the method of this invention, where automation is desired, the method can additionally involve providing a linear slide positioned generally transverse to the webs and having a vacuum table slidably mounted thereon and moveable between valve loading and valve insertion positions. Pneumatic vacuum ports are provided on the vacuum table to retain the valve thereon, and the table is advanced along the slide assembly in timed fashion to spread the webs and insert the valve between the top and bottom webs at the open zone adjacent to the spreader bar. Thereafter, the vacuum table is retracted so that the webs are brought back into a contiguous relation about the valve and the webs frictionally retain the valve therebetween in the correct position. The webs and valve are then conveyed to a die station where the peripheral shape of an inflatable body is formed. To yet further automate the process, a valve feeding mechanism can then be located adjacent the linear slide and vacuum table for automatically supplying the preformed valves and placing them on the vacuum table when the latter is positioned at the valve loading position.
In another embodiment of this invention, the method comprises separating the webs and inserting the valve between the webs directly at the die station so that the valve is inserted directly at the position where it will be permanently attached to the webs when the inflatable body shape is formed. The method includes the steps of conveying the webs in a contiguous relation to the die station, providing a spreader bar at or otherwise adjacent the die station to create an open zone at the die station, and then spreading the webs and inserting the valve between the webs at the open zone and depositing the valve at the desired valve location. The vacuum table or other means for inserting the valve between the webs is then withdrawn from between the webs and a die stamp or other means is used to form a peripheral heat seal of the inflatable body shape which also simultaneously seals the webs to the valve.
The apparatus of this invention comprises a conveying means for conveying the top and bottom webs from source rolls to a die station in a substantially contiguous relation except for at a valve insertion station. Splitting, i.e. spreader bar, means are provided at the valve insertion station means for spreading peripheral edges of the webs apart to form an open zone. Valve insertion means are provided for spreading the webs and inserting a valve between the top and bottom webs at the open zone. Preferably, the valve insertion means take the form of a linear slide positioned generally transverse to the webs and having a vacuum table slidably mounted thereon. The vacuum table is provided with vacuum ports for retaining a valve thereon. In operation, the valve is placed under the vacuum table, manually or by machine, and the vacuum table is advanced through the open zone to a valve insertion position between the upper and lower webs. A die station is provided for heat sealing the perimeter of an inflatable body shape on the webs and simultaneously heat sealing the valve to both of the webs. The valve insertion means may be provided upstream of the die station so that the webs are conveyed together with a valve frictionally retained during the film conversion process to the die station. However, the valve insertion means may alternatively be positioned adjacent to the die station so that the valve is inserted between the webs and deposited at a valve location on the webs directly where it will be sealed to both webs by the die station.
Preferably, the materials of which the valves and webs are comprised are selected based on their high instance of surface adhesion that occurs between the webs and the valve. Examples of such materials include constructing the webs of thin layers of high density polyethylene, linear low density polyethylene, and polypropylene or a combination of these materials.
In the situation where inflatable dunnage bags are being produced, for example, the valve can be inserted between the webs so that at least a portion of the valve, preferably at least 1 inch or more, extends out from between the peripherally sealed film webs making up the bag body. Such valve extension is to permit quick filling of the dunnage bag with air.
Other objects, features, and advantages of the present invention will become apparent from the following specification and drawings.